The 2005 eruption of Sierra Negra volcano, Galapagos, Ecuador
The 2005 eruption of Sierra Negra volcano, Galapagos, Ecuador
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DOI：
10.1007/s00445-007-0160-3
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发表时间：
2008-04-01
影响因子：
3.5
通讯作者：
Rader, Erika
中科院分区：
文献类型：
--
作者：
Geist, Dennis J.;Harpp, Karen S.;Rader, Erika
Sierra Negra火山于2005年10月22日开始爆发，经过26年的休眠。火山喷发的初始阶段伴随着一股超过13公里高的火山灰和蒸汽，随后很快就出现了一个类似于2公里长的熔岩喷泉幕。喷发裂缝打开内的破火山口的北部边缘，在火山口的对面，从一个活跃的断层系统，经历了m（B）4.6地震和类似的84厘米的隆起在2005年4月16日。火山爆发的主要产物是在破火山口形成的熔岩流和从北侧流下的碎屑熔岩。水流以一种不寻常的方式增长。一旦它建立了大部分的空中范围，内部的流动是通过一个栖息的熔岩池，造成膨胀的一个。这种加压的流体内部然后沿着流动的边缘沿着供给绳状熔岩突破口，其中许多随后被a覆盖，因为地壳从池塘的中心缓慢地扩散并在绳状熔岩上翻滚。熔岩喷泉的帷幕随着时间的推移而合并，到第四天，只有一个喷口在喷发。渗出率从第7天开始减慢，直到两天后的10月30日喷发结束。虽然自1992年以来，破火山口底部已经膨胀了大约5米，并且自2003年以来膨胀速度加快，但在喷发前的几个小时或几天内没有短暂的变形。在8天的喷发期间，GPS和干涉合成孔径雷达数据显示，破火山口底部收缩了约5米，火山水平收缩了约6米。总喷发体积估计为150 × 10（6）m（3）。早期火山灰比随后的喷发产物更进化。火山灰和熔岩的成分变化采样的过程中的喷发是由于从一个分区的窗台，位于2.1公里以下的破火山口地板喷发。
Sierra Negra volcano began erupting on 22 October 2005, after a repose of 26 years. A plume of ash and steam more than 13 km high accompanied the initial phase of the eruption and was quickly followed by a similar to 2-km-long curtain of lava fountains. The eruptive fissure opened inside the north rim of the caldera, on the opposite side of the caldera from an active fault system that experienced an m(b) 4.6 earthquake and similar to 84 cm of uplift on 16 April 2005. The main products of the eruption were an a a flow that ponded in the caldera and clastigenic lavas that flowed down the north flank. The a a flow grew in an unusual way. Once it had established most of its aerial extent, the interior of the flow was fed via a perched lava pond, causing inflation of the a a. This pressurized fluid interior then fed pahoehoe breakouts along the margins of the flow, many of which were subsequently overridden by a a, as the crust slowly spread from the center of the pond and tumbled over the pahoehoe. The curtain of lava fountains coalesced with time, and by day 4, only one vent was erupting. The effusion rate slowed from day 7 until the eruption's end two days later on 30 October. Although the caldera floor had inflated by similar to 5 m since 1992, and the rate of inflation had accelerated since 2003, there was no transient deformation in the hours or days before the eruption. During the 8 days of the eruption, GPS and InSAR data show that the caldera floor deflated similar to 5 m, and the volcano contracted horizontally similar to 6 m. The total eruptive volume is estimated as being similar to 150x10(6) m(3). The opening-phase tephra is more evolved than the eruptive products that followed. The compositional variation of tephra and lava sampled over the course of the eruption is attributed to eruption from a zoned sill that lies 2.1 km beneath the caldera floor.